The United States Department of Energy (DOE) is an executive department of the U.S. federal government that oversees U.S. national energy policy and manages the research and development of nuclear power and nuclear weapons in the United States. The DOE oversees the U.S. nuclear weapons program, nuclear reactor production for the United States Navy, energy-related research, and domestic energy production and energy conservation.

The DOE was created in 1977 in the aftermath of the 1973 oil crisis. It sponsors more physical science research than any other U.S. federal agency, the majority of which is conducted through its system of National Laboratories. The DOE also directs research in genomics, with the Human Genome Project originating from a DOE initiative.

The department is headed by the Secretary of Energy, who reports directly to the president of the United States and is a member of the Cabinet. The current Secretary of Energy is Jennifer Granholm, who has served in the position since February 2021. The department's headquarters are in southwestern Washington, D.C., in the James V. Forrestal Building, with additional offices in Germantown, Maryland.